Battery pack and manufacturing method therefor

Abstract

The present disclosure provides a battery pack comprising one or more heat-absorbing members which each have one or more batteries, a heat-absorbing agent, and an accommodation body that accommodates the heat-absorbing agent, wherein: the accommodation body includes a welded part of a laminated structure film; the laminated structure film has a structure in which a metal layer and a resin layer positioned inside the metal layer are laminated; the welded part has a first welded portion and a second welded portion positioned outside the first welded portion; and the resin layer of the second welded portion is thinner than the resin layer of the first welded portion.

Description

Battery pack and manufacturing method thereof

[0001] The present disclosure relates to a battery pack and a method for manufacturing the same.

[0002] Patent Document 1 discloses a battery module including a battery unit, a housing for accommodating the battery unit, and a heat-absorbing member provided in contact with the side surface of the battery. Patent Document 1 discloses that the heat-absorbing member contains an endothermic agent containing water as a main component, and that the air and the endothermic agent inside the heat-absorbing member expand, causing an increase in internal pressure to release the endothermic agent.

[0003] WO2010 / 098067

[0004] Here, the conventional technology has the following points that need to be improved.

[0005] As described above, the heat-absorbing member contains an endothermic agent by fusing (corresponding to welding) an exterior film having a metal film and a resin film. The fused portion is formed by fusing together the resin films, and since the endothermic agent in the heat-absorbing member is primarily composed of water, it is necessary to suppress water vapor permeation through the fused portion, particularly the resin film (corresponding to the resin layer), during normal battery use. Furthermore, when the battery reaches a high temperature within the normal use range during normal battery use, it is necessary to ensure peel strength sufficient to withstand peeling of the fused portion, particularly the resin film (corresponding to the resin layer), due to evaporation of the water-based endothermic agent and the resulting expansion.

[0006] Therefore, an object of the present disclosure is to provide a battery pack including a heat-absorbing member including a welded portion that can suppress water vapor permeation and ensure peel strength during normal use of the battery, and a manufacturing method thereof.

[0007] In order to achieve the above object, the present disclosure provides a battery pack comprising: one or more heat-absorbing members having one or more batteries; a heat-absorbing agent; and a housing that accommodates the heat-absorbing agent; wherein the housing includes a welding portion of a laminated structure film, the laminated structure film having a structure in which a metal layer and a resin layer located inside the metal layer are laminated; and the welding portion has a first welding portion and a second welding portion located outside the first welding portion, and the resin layer of the second welding portion is thinner than the resin layer of the first welding portion.

[0008] In order to achieve the above object, the present disclosure provides a method for manufacturing a battery pack, including a step of fabricating a heat-absorbing member, wherein the step of fabricating the heat-absorbing member includes a step of using one or more laminated structure films having a metal layer and a resin layer laminated on the metal layer to form a welded portion at a location other than the predetermined location of the laminated structure film so that the predetermined location can accommodate a heat-absorbing agent, and in the step of forming the welded portion, predetermined locations of the resin layers are bonded together, and a first welded portion and a second welded portion are formed so that the resin layer of the second welded portion is thinner than the resin layer of the first welded portion.

[0009] The battery pack of the present disclosure can provide a heat-absorbing member including a welded portion that can simultaneously suppress water vapor permeation and ensure peel strength during normal battery use.

[0010] Fig. 4 is an exploded perspective view schematically showing a battery pack according to the present disclosure; Fig. 5 is an exploded perspective view schematically showing a core pack in the battery pack according to the present disclosure; Fig. 6 is a perspective view schematically showing a heat-absorbing member (when the battery is in normal use) in the battery pack according to the present disclosure; Fig. 7 is a partially enlarged cross-sectional view schematically showing a heat-absorbing member in the area surrounded by dotted lines in Fig. 3; Fig. 8 is a partially enlarged cross-sectional view schematically showing a heat-absorbing member having a welded part with a constant thickness; Fig. 9 is a partially enlarged cross-sectional view schematically showing a state in which resin layers of a laminated structure film are bonded together and a first welded part and a second welded part are formed in a process of producing a welded part of the heat-absorbing member;

[0011] A battery pack according to an embodiment of the present disclosure will be specifically described below with reference to the drawings. Although the description will be made with reference to the drawings as needed, the various elements in the drawings are merely shown schematically and as examples to facilitate understanding of the present disclosure, and the appearance, dimensional ratios, etc. may differ from the actual product.

[0012] Various numerical ranges mentioned in this specification are intended to include the lower and upper limit numerical values ​​themselves, unless otherwise specified, such as "less than" or "more than / greater than." For example, a numerical range such as 1 to 10 can be interpreted as including the lower limit of "1" and the upper limit of "10." Furthermore, terms such as "about" and "approximately" mean that the range may include a variation of a few percent, for example, ±10%.

[0013] The overall configuration of the battery pack of the present disclosure will be described below. Fig. 1 is an exploded perspective view schematically showing the battery pack of the present disclosure. Fig. 2 is an exploded perspective view schematically showing a core pack in the battery pack of the present disclosure. Fig. 3 is a perspective view schematically showing a heat-absorbing member in the battery pack of the present disclosure (when the battery is in normal use). Fig. 4 is a partially enlarged cross-sectional view schematically showing the heat-absorbing member in the area enclosed by the dotted line in Fig. 3.

[0014] 1 and 2 , the battery pack 1000 of the present disclosure includes one or more batteries 200, a battery holder 100 capable of housing the batteries 200, tabs 400 that electrically connect the batteries 200, a substrate 500 connected to the tabs, and an exterior body 600 that houses the integrated assembly (hereinafter referred to as a battery core pack). The battery 200 may be, for example, a cylindrical battery or a prismatic battery. The following description will be given taking the case where the battery 200 is a cylindrical battery as an example.

[0015] (Exterior Body) The exterior body 600 may be any body capable of stably housing the above-described battery core pack. The exterior body 600 may have a main body and a lid that can be combined with the main body. The exterior body 600 is provided with external terminals 610 connected to the substrate 500. The battery 200 is electrically connected to the external terminals 610 via the substrate 500. In addition to the above-described battery 200, the battery holder 100 can house one or more heat-absorbing members 300 (described below) that are provided so as to be in contact with the side surfaces of the battery 200. When multiple batteries 200 are provided, the heat-absorbing members 300 can be disposed between one battery 200 and the other battery 200.

[0016] The exterior body 600 may be made of any material, including a resin material (e.g., plastic) or a metal material. Examples of resin materials include polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polybutylene terephthalate (PBT), modified polyphenylene ether (m-PPE), and polyamide (PA). Examples of metal materials include aluminum. Note that, in consideration of the safety of the battery pack, it is preferable to use an insulating material.

[0017] (Battery) As shown in Fig. 2, the battery 200 is accommodated in a housing portion (described later) of the battery holder 100. The battery 200 has electrodes accommodated in an outer can 201 with a bottom, and is filled with an electrolyte, with the opening of the outer can 201 closed with a sealing plate 202. The bottom surface of the outer can 201, which is one of both end surfaces, and electrodes provided on the sealing plate 202 serve as positive and negative electrode terminals of the battery 200. For example, the battery 200 may be a lithium-ion secondary battery that can be charged and discharged.

[0018] It should be noted that, with regard to the battery designated by the reference numeral 200 described above based on FIG. 2, even when no other reference numeral is specifically assigned hereinafter in this specification, the battery will refer to the battery designated by the reference numeral 200 (see FIG. 2).

[0019] 2, the battery holder 100 has a housing portion 101 capable of housing a battery 200 therein, and an enclosure portion 102 that defines at least a portion of the housing portion 101. In this specification, the enclosure portion 102 may also be referred to as a housing portion, a main body portion, a body portion, or a wall portion.

[0020] When multiple batteries 200 are used, a predetermined portion of the enclosure 102 of the housing 101 located between adjacent batteries 200 functions as a partition between the batteries 200. The housing 101 is a space capable of housing the batteries 200. As an example, when the enclosure 102 defines a portion of the housing 101, the heat-absorbing member 300 disposed within the battery holder 100 can define the remainder or other portions of the housing 101 other than the enclosure 102. In other words, the heat-absorbing member 300 and the enclosure 102 of the battery holder 100 form the outline of the housing 101 that houses the batteries 200. In this case, most of the outline of the housing 101 can be continuous.

[0021] 2, the battery holder 100 is composed of multiple battery holder parts 110, 120 that are divided in the axial direction of the battery 200 housed in the battery holder 100. In other words, the battery holder 100 is composed of multiple battery holder parts 110, 120 that are interconnected along the axial direction.

[0022] The shape of the enclosure 102 of the battery holder 100 and the shape of the outer surface of the heat absorption member 300 depend on the cross-sectional shape of the cylindrical battery 200 to be housed or inserted. For example, as shown in Figure 2, if the cross-sectional shape of the battery 200 is circular, the shape of the enclosure 102 of the battery holder 100 and the shape of the outer surface of the heat absorption member 300 can also be curved to correspond to that circular shape.

[0023] 2 coincides with the central axis of the space in the housing section 101. In this case, when the batteries 200 are housed in the housing section 101, the distance between the central axis of one adjacent battery 200 and the central axis of the other adjacent battery 200 is unlikely to change, and therefore tab attachment using the tab 400 that electrically connects the batteries 200 to each other can be easily performed.

[0024] From the above, when the battery 200 is placed in the storage section 101 of the battery holder 100, the battery 200, the heat absorption member 300 and the enclosure 102 of the battery holder 100 can be arranged so that the outer circumferential edge of the battery 200 can face each of the enclosure 102 of the battery holder 100 and the heat absorption member 300 arranged adjacent to the enclosure 102 in the same circumferential direction.

[0025] The battery holder 100 is molded into a predetermined shape from an insulating resin such as a thermoplastic resin, for example, PC (polycarbonate) or PP (polypropylene).

[0026] (Tab) A pair of tabs 400 may be provided corresponding to the positive and negative terminals of the battery 200. By supplying power from the battery 200 to the board 500 via the tabs 400, the board can be operated as a control board.

[0027] Furthermore, when a plurality of batteries 200 are used, the tabs 400 electrically connect adjacent batteries 200. The batteries 200 may be electrically connected in series or in parallel by the tabs 400. To achieve such electrical connection, the tabs 400 are preferably made of a material with good electrical conductivity.

[0028] 2, 3, and 4, the heat absorption member 300 is provided so as to be in contact with the side surface of the battery 200 as described above, and includes a heat absorption agent 310 and a housing 320 that houses the heat absorption agent 310. The housing 320 includes a main body 321 that houses the heat absorption agent 310, and a welding portion 322 that is continuous with the main body 321 and seals the main body 321. In the drawings, the main body 321 of the housing 320 refers to a relatively large main portion, and the welding portion 322 of the housing 320 refers to a protruding portion or tab portion that is configured to protrude in the transverse or lateral direction from the main body 321.

[0029] The housing 320 may be made of a laminated film 323 as an exterior film. The heat-absorbing agent 310 is primarily composed of a liquid such as water, and may contain a gelling agent to facilitate handling and a surfactant to improve hydrophilicity. Examples of gelling agents that can be used include polyvinyl alcohol and sodium polyacrylate. The content of the liquid such as water in the heat-absorbing agent may be, for example, 50% to 99% by weight.

[0030] The laminated structure film 323 has a laminated structure in which a metal layer 324 located on the outside and a resin layer 325 located on the inside of the metal layer 324 are stacked. The metal layer 324 can be configured to be able to suppress water vapor transmission to the outside, which is caused by the heat-absorbing agent 310, which is mainly composed of water and located inside the main body 321. The resin layer 325 can be configured to be able to maintain the shape and strength of the housing 320.

[0031] As an example, the main body 321 of the housing 320 has a two-layer structure made up of a metal layer 324 and a resin layer 325 laminated inside the metal layer 324. The welded portion 322 of the housing 320 has a three-layer structure made up of metal layers 324 laminated on both sides of the resin layer so as to sandwich the resin layer 325.

[0032] The metal layer 324 may be formed of, for example, an Al layer. The resin layer 325 may be made of polyethylene terephthalate (PET), polyethylene, polypropylene, etc. The thickness of the metal layer 324 and the resin layer 325 may be approximately several tens of μm.

[0033] The welded portion 322 may be formed by welding a predetermined portion of one resin layer of the two laminated films to a predetermined portion of the other resin layer, or by folding one laminated film and welding a predetermined portion of the resin layer to another portion.

[0034] When a predetermined portion of the battery 200 generates abnormal heat, the heat-absorbing agent 310 in the heat-absorbing member 300 close to the abnormally heated portion of the battery 200 expands, causing an increase in internal pressure. This causes the heat-absorbing member 300 to split, allowing the heat-absorbing agent 310 to be released to the outside from the split location. The split location may be the welded portion 322 that seals the main body portion 321.

[0035] (Characteristic Parts of the Present Disclosure) Having explained the above configuration, the following describes the characteristic parts of the present disclosure. The present disclosure is characterized by the configuration of the welded part 322, which is a component of the heat-absorbing member 300 described above, during normal use.

[0036] Specifically, the present disclosure is characterized in that the welded portion 322 has a first welded portion 322a and a second welded portion 322b located outside the first welded portion 322a, and the resin layer 325b of the second welded portion 322b is thinner than the resin layer 325a of the first welded portion 322a. That is, the thickness t(2) of the resin layer 325b in the second welded portion 322b is thinner than the thickness t(1) of the resin layer 325a in the first welded portion 322a.

[0037] In this regard, second welded portion 322b is located outside first welded portion 322a, and its end face can serve as end face 326 of welded portion 322. In this case, end face 326 of welded portion 322 can be exposed to the outside, which raises concerns that water vapor within housing 320 (in other words, vaporized from heat-absorbing agent 310) can permeate to the outside from end face 326 of welded portion 322 (corresponding to the end face of second welded portion 322b) through the resin layer within welded portion 322.

[0038] In the present disclosure, second welded portion 322b having relatively thin resin layer 325b is located outside first welded portion 322a having relatively thick resin layer 325a, and therefore, as shown in Fig. 5 , it is possible to suppress the permeation of water vapor to the outside during normal use of battery 200 compared to when the thickness of resin layer 325 in welded portion 322' is constant overall at t(1)'. In other words, it is possible to preferably suppress the permeation of water vapor to the outside through welded portion 322 during normal use of battery 200.

[0039] Furthermore, when the battery is in normal use and reaches a high temperature within the normal operating range, there is a concern that the water-based heat-absorbing agent 310 contained in the main body 321 of the housing 320 will evaporate and expand, possibly causing peeling of the welded portion 322. This peeling is likely to occur at the first welded portion 322a proximal to the main body 321 of the housing 320, where the force of the internal pressure caused by the expansion is easily transmitted.

[0040] In this regard, in the present disclosure, first welded portion 322a having relatively thick resin layer 325a is located more inward than second welded portion 322b having relatively thin resin layer 325b. Therefore, first welded portion 322a, which is proximal to main body 321 of container 320 and through which the force of internal pressure caused by expansion is easily transmitted, can be provided with an appropriate peel strength capable of withstanding peeling of resin layer 325a located on the inner side.

[0041] As described above, the welded portion 322 of the heat-absorbing member 300 having the above-described characteristic configuration can suppress water vapor permeation and ensure peel strength during normal battery use. Specifically, the heat-absorbing agent 310 inside can be prevented from leaking except when the battery 200 generates abnormal heat. In other words, the laminated structure film 323 of the heat-absorbing member 300 has the above-described structure, which stably holds the heat-absorbing agent 310 inside and ensures high safety over a long period of time.

[0042] The welded portion 322 may have a first welded portion 322a having a predetermined thickness and a second welded portion 322b that is thinner than the first welded portion 322a and located outside the first welded portion 322a. In this case, a laminated structure film 323 having a metal layer 324 with a constant thickness may be used. Here, "the thickness of the metal layer 324 is constant" does not necessarily mean that the thickness of the metal layer 324 is completely uniform throughout the entire laminated structure film 323, but may also mean that the thickness of the metal layer 324 is 90% to 110% of the thickness of a predetermined portion of the metal layer 324.

[0043] That is, the welded portion 322 may be composed of two or more welded portions with different thicknesses. Here, the "second welded portion 322b" refers to the welded portion that is located outermost and has the smallest thickness among the two or more welded portions that make up the welded portion 322. In this case, the end surface 326 of the welded portion 322 may be the end surface of the second welded portion 322b. Therefore, another welded portion that is thinner than the first welded portion 322a and thicker than the second welded portion 322b may be further included between the first welded portion 322a and the second welded portion 322b.

[0044] Furthermore, the thickness of the resin layer 325a in the first welded portion 322a of the welded portion 322 may be less than twice the thickness of the resin layer 325 in a portion other than the welded portion 322, for example, in the main body portion 321. As described above, the welded portion 322 is obtained by thermally welding or ultrasonically welding the bonded portions of one or more laminated structure films 323 at predetermined locations. Welding is a technique for applying heat or the like to predetermined locations of the laminated structure film 323 to melt them, applying pressure to bring the melted portions together, and cooling to bond them, and includes processes such as melting.

[0045] Therefore, as described above, after welding, the thickness of resin layer 325a at first welded portion 322a can be less than twice the thickness of resin layer 325 at locations other than welded portion 322. By making the thickness less than twice as large, it is possible to improve the strength of resin layer 325a at first welded portion 322a and suppress water vapor transmission through main body portion 321, compared to when the two portions are simply bonded together.

[0046] Furthermore, the thickness of the resin layer 325b in the second welded portion 322b of the welded part 322 is thinner than the thickness of the metal layer 324b in the second welded portion 322b. With this configuration, the thickness of the metal layer 324b in the second welded portion 322b is relatively large, while the thickness of the resin layer 325b is relatively small. Therefore, as described above, the relatively small thickness of the resin layer 325b in the second welded portion 322b suppresses water vapor permeation, and the relatively large thickness of the metal layer 324b in the second welded portion 322b suppresses water vapor permeation of the metal layer 324b.

[0047] Furthermore, the first welded portion 322a and the second welded portion 322b may be continuous. In this case, since the second welded portion 322b is thinner than the first welded portion 322a, a continuous portion 327 between the first welded portion 322a and the second welded portion 322b may have an inclined surface 328 rather than a flat surface.

[0048] Specifically, because the second welded portion 322b is thinner than the first welded portion 322a, the inclined surface 328 of the continuous portion 327 extends obliquely upward and downward from the first welded portion 322a to the second welded portion 322b in a cross-sectional view. In other words, the continuous portion 327 is tapered from the first welded portion 322a to the second welded portion 322b.

[0049] With this structure, welded portion 322 can gradually narrow the width of the route through which water vapor can permeate from two main body portions 321 at continuous portion 327. This makes it possible to suitably suppress water vapor permeation into the region of resin layer 325b in second welded portion 322b having an end face that can be exposed to the outside.

[0050] Furthermore, the width W2 of the second welded portion 322b of the welded portion 322 is larger than the width W1 of the first welded portion 322a. This configuration allows the size of the second welded portion 322b, whose end face is in contact with the outside, in the cross-sectional view of FIG. 4 (i.e., the transverse direction of the second welded portion 322b where it is desired to suppress water vapor transmission to the outside) to be increased. Specifically, the length from one end face of the second welded portion 322b proximal to the first welded portion 322a to the other end face of the second welded portion 322b distal to the first welded portion 322a (corresponding to the end face 326 of the welded portion 322) can be increased. This effectively prevents water vapor from transmitting to the outside from the end face of the second welded portion 322b that corresponds to the end face 326 of the welded portion 322.

[0051] The manufacturing method of the battery pack of the present disclosure will be described below, focusing in particular on the manufacturing process of the heat-absorbing member 300.

[0052] In the process of manufacturing this heat-absorbing member 300, first, a laminated structure film 323 is prepared, which has a metal layer 324 and a resin layer 325 laminated on the metal layer 324. Then, welded portions 322 are formed by thermal welding or ultrasonic welding at locations (locations that become welded portions 322) other than the predetermined locations (locations that become main body portion 321) of laminated structure film 323 so that heat-absorbing agent 310 can be accommodated in the predetermined locations (locations that become main body portion 321).

[0053] As one example, a predetermined location of one resin layer 325 of two laminated structure films 323 is welded to a predetermined location of the other resin layer 325 to form the welded portion 322. As another example, one laminated structure film 323 is folded and a predetermined location of the resin layer 325 is welded to another location to form the welded portion 322.

[0054] In particular, in the present disclosure, as shown in Fig. 6, the resin layers 325 of one or two laminated structure films 323 are bonded together, and the first welded portion 322a and the second welded portion 322b are formed so that the resin layer 325 of the second welded portion 322b is thinner than the resin layer 325 of the first welded portion 322a. In one embodiment, the first welded portion 322a and the second welded portion 322b can be formed simultaneously. In another embodiment, the first welded portion 322a and the second welded portion 322b may be formed at different times.

[0055] Furthermore, based on the above-described formation mode, the first welded portion 322a and the second welded portion 322b can be formed so that the welded portion 322 has the first welded portion 322a of a predetermined thickness and the second welded portion 322b that is thinner than the first welded portion 322a and is located outside the first welded portion 322a. In this case, a laminated structure film 323 in which the thickness of the metal layer 324 is constant can be used.

[0056] As a means for forming the first welded portion 322a and the second welded portion 322b, for example, a pair of stepped heat blocks P (or horns) can be used.

[0057] Specifically, a pair of stepped heat blocks P are arranged so as to sandwich the resin layers 325 of the one or two laminated films 323 before welding between the pair of stepped heat blocks P. The inner surface P1 of each stepped heat block P must have a shape corresponding to the desired outer surface shape of the resulting welded portion 322. That is, from a state in which the resin layers 325 of the one or two laminated films 323 are spaced apart before welding, the welded portion 322 having the first welded portion 322a and the second welded portion 322b is formed in a single process (which may also be referred to as one-step processing).

[0058] In this manner, the heat-absorbing member 300 used in the present disclosure can be produced. The housing 320 of the heat-absorbing member 300 has a main body 321 that accommodates the heat-absorbing agent 310, and a welded portion 322 that is continuous with the main body 321, seals the main body 321, and has welded portions of different thicknesses as described above. Therefore, the heat-absorbing member 300 having the welded portion 322 can suppress water vapor permeation and ensure peel strength during normal use of the battery 200.

[0059] A battery core pack can be obtained by accommodating the heat absorption member 300 and the battery 200 in the battery holder 100 so that they can come into contact with the side surface of the battery 200, and then providing the battery holder 100 in the accommodated state with a tab 400 so that the battery 200 can be electrically connected to the tab 400, and providing a substrate 500 so that the tab 400 can be electrically connected to the battery core pack. Finally, the battery pack 1000 of the present disclosure can be manufactured by accommodating the battery core pack in the exterior body 600.

[0060] When forming a welded portion 322 in which the first welded portion 322a and the second welded portion 322b are continuous, the first welded portion 322a and the second welded portion 322b are formed so that a continuous portion 327 between the first welded portion 322a and the second welded portion 322b has an inclined surface 328. The inclination angle of this inclined surface 328 is preferably 5 degrees or more and 40 degrees or less with respect to a virtual horizontal plane 329. If the inclination angle exceeds this range, there is a risk of peeling between the metal layer 324 and the resin layer 325.

[0061] If the resin layers 325 of the one or two laminated structure films 323 are spaced apart from each other before welding, and then a welding portion 322 having a first welding portion 322a and a second welding portion 322b is formed over time by two-stage processing, the molten resin from the second processing step may be pushed out toward the melted area from the first processing step, and a force may act to cause the resin to overflow into the melted area from the first processing step, or the resin may try to bulge in the thickness direction.

[0062] Therefore, shear stress is applied to the interface between the metal layer 324 and the resin layer 325, which may lead to delamination between the metal layer 324 and the resin layer 325. In light of this, it is preferable to form the welded portion 322, which has the first welded portion 322a and the second welded portion 322b, in a single process (which may also be referred to as one-step processing). This reduces the shear stress applied to the interface between the resin layer 325 and the metal layer 324, and effectively prevents delamination between the metal layer 324 and the resin layer 325.

[0063] It should be noted that the embodiments disclosed herein are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present disclosure should not be interpreted solely by the above-described embodiments, but should be defined based on the claims. The technical scope of the present disclosure also includes all modifications within the scope and meaning equivalent to the claims.

[0064] The present disclosure includes the following aspects. <1> A battery pack comprising: one or more heat-absorbing members having one or more batteries; a heat-absorbing agent; and a housing that accommodates the heat-absorbing agent, wherein the housing includes a welded portion of a laminated film, the laminated film having a structure in which a metal layer and a resin layer located inside the metal layer are laminated, and the welded portion has a first welded portion and a second welded portion located outside the first welded portion, and the resin layer at the second welded portion is thinner than the resin layer at the first welded portion. <2> The battery pack described in <1>, wherein the thickness of the resin layer of the laminated film at the first welded portion of the welded portion is less than twice the thickness of the resin layer at a location other than the welded portion. <3> The battery pack described in <1> or <2>, wherein the thickness of the resin layer at the second welded portion of the welded portion is thinner than the thickness of the metal layer at the second welded portion. <4> The battery pack according to any one of <1> to <3>, wherein the first welded portion and the second welded portion are continuous, and the continuous portion between the first welded portion and the second welded portion has an inclined surface. <5> The battery pack according to <4>, wherein the inclined surface of the continuous portion extends obliquely upward and downward from the first welded portion to the second welded portion. <6> The battery pack according to any one of <1> to <5>, wherein the first welded portion and the second welded portion are continuous, and the continuous portion between the first welded portion and the second welded portion tapers from the first welded portion to the second welded portion. <7> The battery pack according to any one of <1> to <6>, wherein the width of the second welded portion of the welded portion is larger than the width of the first welded portion. <8> The battery pack according to any one of <1> to <7>, wherein an end face of the second welded portion of the welded portion is the end face of the welded portion that comes into contact with the outside. <9> The battery pack according to any one of <1> to <8>, wherein the welded portion has a first welded portion of a predetermined thickness and a second welded portion that is thinner than the first welded portion and is located outside the first welded portion. <10> The battery pack according to any one of <1> to <9>, wherein the metal layer has a constant thickness.<11> A battery pack manufacturing method including a heat-absorbing member fabrication step, wherein the heat-absorbing member fabrication step includes a step of using one or more laminated structure films having a metal layer and a resin layer laminated on the metal layer to form welded portions at locations other than the predetermined locations of the laminated structure film so that the predetermined locations can accommodate a heat-absorbing agent, and wherein the welded portion forming step includes bonding the predetermined locations of the resin layers together and forming a first welded portion and a second welded portion so that the resin layer at the second welded portion is thinner than the resin layer at the first welded portion. <12> The manufacturing method according to <11>, wherein the welded portion forming step includes forming the first welded portion and a second welded portion so that the welded portion has a first welded portion of a predetermined thickness and a second welded portion that is thinner than the first welded portion and is located outside the first welded portion. <13> The manufacturing method according to <11> or <12>, wherein a laminated structure film having the metal layer with a constant thickness is used.

[0065] The battery pack of the present disclosure can be used primarily as a power source for motive power, for example, power tools, power-assisted bicycles, and other motor-driven electric devices.

[0066] REFERENCE SIGNS 100 Battery holder 101 Storage section 102 Wall section 110 Battery holder component 120 Battery holder component 200 Battery 201 Outer can 202 Sealing plate 300 Heat absorption member 310 Heat absorption agent 320 Storage body 321 Main body 322 Welded section 322a First welded section 322b Second welded section 323 Laminated structure film 324 Metal layer 325 Resin layer 326 End surface of welded section 327 Connecting section between first welded section and second welded section 328 Inclined surface of connecting section between first welded section and second welded section 329 Virtual horizontal plane 400 Tab 500 Substrate 600 Exterior body 1000 Battery pack P Stepped heat block P1 Inner surface of stepped heat block W1 Width of second welded portion W2 Width of first welded portion

Claims

1. One or more batteries, One or more heat-absorbing members, each comprising a heat-absorbing agent and a housing for containing the heat-absorbing agent. Equipped with, The housing includes a welded portion of a laminated film, and the laminated film has a structure in which a metal layer and a resin layer located inside the metal layer are laminated, and The welding portion comprises a first welding portion and a second welding portion located outside the first welding portion, wherein the resin layer of the second welding portion is thinner than the resin layer of the first welding portion, in a battery pack.

2. The battery pack according to claim 1, wherein the thickness of the resin layer of the laminated film in the first welded portion of the welded portion is less than twice the thickness of the resin layer in portions other than the welded portion.

3. The battery pack according to claim 1, wherein the thickness of the resin layer in the second welded portion of the welded portion is thinner than the thickness of the metal layer in the second welded portion.

4. The battery pack according to claim 1, wherein the first welded portion and the second welded portion are continuous, and the continuous portion of the first welded portion and the second welded portion has an inclined surface.

5. The battery pack according to claim 4, wherein the inclined surface of the continuous portion extends diagonally upward and downward from the first welded portion to the second welded portion.

6. The battery pack according to claim 1, wherein the first welded portion and the second welded portion are continuous, and the continuous portion between the first welded portion and the second welded portion is tapered from the first welded portion to the second welded portion.

7. The battery pack according to claim 1, wherein the width of the second welded portion of the welded portion is greater than the width of the first welded portion.

8. The battery pack according to claim 1, wherein the end face of the second welded portion of the welded portion is the end face of the welded portion that is in contact with the outside.

9. The battery pack according to claim 1, wherein the welded portion comprises a first welded portion of a predetermined thickness and a second welded portion that is thinner than the first welded portion and located outside the first welded portion.

10. The battery pack according to claim 1, wherein the thickness of the metal layer is constant.

11. A method for manufacturing a battery pack, including a step for manufacturing a heat-absorbing member, The process for manufacturing the heat-absorbing member includes a step of using one or more laminated structural films having a metal layer and a resin layer laminated on the metal layer, and forming a welded portion at a location other than the predetermined location so that a heat-absorbing agent can be contained at a predetermined location on the laminated structural film, A method for manufacturing a battery pack, comprising the step of forming the welded portion, wherein predetermined portions of the resin layers are bonded together, and the formation of the first welded portion and the second welded portion are carried out such that the resin layer of the second welded portion is thinner than the resin layer of the first welded portion.

12. The manufacturing method according to claim 11, wherein in the step of forming the welded portion, the first welded portion and the second welded portion are formed such that the welded portion has a first welded portion of a predetermined thickness and a second welded portion that is thinner than the first welded portion and located outside the first welded portion.

13. The manufacturing method according to claim 11 or 12, wherein a laminated film having the metal layer having a constant thickness is used.